Heat dome to topple records in drought-stricken Plains and Western states
Another heat dome is coming. And it’s about to elevate fire risks and topple temperature records, with heat and/or fire weather alerts in effect for around 33 million people living in stretches of Western and central states as of early Friday.
This heat dome will first sizzle drought-stricken parts of the Intermountain West this weekend before expanding into the northern Plains and upper Midwest next week.
The National Weather Service in Salt Lake City, which serves most of Utah, called it “the most significant heat wave thus far this season” in a forecast discussion, writing that monthly temperature records will be challenged this weekend. It is forecast to reach 106 degrees in Salt Lake City on Sunday, which would tie for the city’s second-highest temperature on record since records began in 1874.
Farther north, temperatures could reach 110 degrees in parts of Idaho, Montana and Wyoming, challenging all-time temperature records in some places, such as Billings, on Sunday – where it could be hotter than Phoenix.
By Monday, the Dakotas will be underneath the planet’s most powerful heat dome, with temperatures easily eclipsing 100 degrees for many – and potentially pushing toward 110 degrees for some, such as people near Rapid City in South Dakota.
And from Monday to Wednesday, temperatures in the stretch from Denver to Minneapolis are forecast to reach well into the 90s.
These hot, dry and windy conditions are expected to increase fire weather risks across the interior West – where drought conditions are worst – and to a lesser extent, California.
In a live stream on Thursday, climate scientist Daniel Swain discussed his concerns for lightning-ignited fires. These fires can take a day or two to show themselves, he said, with trees and bushes smoldering “quietly” after being struck by lightning before turning into an active fire once conditions warm up and dry out.
“I would not at all be surprised to see these risk areas expanded or upgraded from elevated to critical,” he said when discussing fire weather outlooks across the Intermountain West through this weekend.
This developing heat dome is the latest in a string of similar events that have recently scorched Europe and the U.S. East Coast.
The formation of this heat dome can be linked to a building El Niño, which is contributing to stormy weather – including a dangerous typhoon – in parts of the Pacific. That has ripple effects on the jet stream. That ribbon of fast-moving air in the upper atmosphere will form a ridge of high pressure in the West and Plains to compensate for unsettled conditions elsewhere.
But climate change is raising the bar on heat dome intensity, which can create more dangerous conditions – especially when combined with excessive humidity levels, which have risen in recent decades, as well as unusually warm nights.
As the core of the heat dome shifts into the central U.S. next week, some monsoonal moisture will probably flow into the West, increasing the chance for scattered rain and thunderstorm activity.
“By the time we get to mid and late July, there is some good news here, which is that it does look like there are better odds that there is going to be a moister air mass across the West,” Swain added.